The goals of the study are to determine how much of the fat in the diet clears to the liver and is resecreted by the liver as VLDL. Subjects will be admitted to the GCRC and receive stable isotopes by IV and through a feeding tube. Fats infused through the feeding tube will label intestinally produced lipoproteins, which, after they circulate, clear to the liver. The results of the study will help determine why low-fat diets cause elevations in blood triglyceride levels.